FRIED, J. (concurring, with whom Lynch, J., joins).

I agree that the officer acted properly when he activated his blue lights and approached the defendant's vehicle. I also agree that these actions constituted a seizure for purposes of the Fourth Amendment to the United States Constitution and art. 14 of our Declaration of Rights. But I think it stretches a point to say, as does the court, that these actions were justified, under the rule of Terry v. Ohio, 392 U.S. 1 (1968), by a "reasonable suspicion that the defendant was engaged in criminal activity, more specifically, that the defendant was operating while under the influence of alcohol." Ante at 492. And there is no reason to stretch in order to justify the officer's eminently reasonable conduct. The motion judge found that "[t]here was a snowstorm taking place and the road conditions were icy and snowy; cars were sliding and skidding on the roadways." He also found that "[t]he officer lawfully stopped the motor vehicle and engaged the operator in conversation because of what the unknown motorist told him, because of what he observed while following the vehicle, and because the operator with his head slumped over the wheel should be assisted by the police." The motion judge made no finding or ruling that the officer had reason to suspect that the defendant had been operating a vehicle while under the influence of alcohol or that any other unlawful activity was afoot. He simply denied the motion to suppress. Moreover, the officer testified that, at the time he pulled up behind the defendant's vehicle, he had no thought that any violation of law had occurred, but rather that he was investigating whether the operator was lost or having some kind of trouble operating his vehicle under the hazardous condition that then obtained. The officer also testified that other vehicles were also slipping and sliding on the roads because of the very poor conditions. This testimony accords with the findings quoted above. It was on this basis that the Commonwealth briefed and argued this case to us.

In my view this case is controlled by our decision in Commonwealth v. Leonard, 422 Mass. 504, cert. denied, 117 S. Ct. 199 (1996). In Leonard, as here, the police officer noticed circumstances that led him to believe that the motorist, who was lawfully parked in a cut-out area on Storrow Drive in Boston, was in some sort of difficulty. The officer pulled in behind the stopped car and activated his blue lights. The motorist in that case did not complain about the use of the blue lights, but rather that the officer, when he was unable to obtain a response from her, opened her vehicle door. We held:

"Even if opening an unlocked vehicle door, where the police officer is acting out of concern for the well being of the person inside rather than on the basis of a suspicion of criminality, passes some constitutional threshold requiring constitutionally sufficient justification . . . what [the trooper] did here was a minimally intrusive response to one of the myriad and uncategorizable events that may alert an officer that his assistance may be required."

Id. at 508-509. The officer's action in opening the vehicle door in Leonard would have to be categorized as a search, while what we have here is technically a seizure, but the same principles apply.

I do not know why the court stretches to justify the seizure in this case as an exercise in criminal law enforcement when the officer's testimony, the objective circumstances, and the Commonwealth's theory of the case present a clear instance of another and entirely sufficient justification, what has long been recognized as the exercise of the "community caretaking" function. Cady v. Dombrowski, 413 U.S. 433, 441 (1973). The motion judge's findings also point in this direction and certainly speak not at all of reasonable suspicion nor of criminality. I do not understand why the court assumes that the nightstick and revolver rather than the helping hand are the more natural or the inevitable way of conceptualizing police action.

Our decision in Leonard, which clearly rested on the community caretaking justification, broke no new ground. On the contrary, the cases are literally legion in which police action involving a search or seizure is justified not by any reference to a law enforcement function but under this community caretaking rationale. See, e.g., United States v. Rohrig, 98 F.3d 1506, 1518-1522 (6th Cir. 1996) (entry to quell loud and disruptive noise in residential neighborhood is sufficiently compelling to justify warrantless intrusions in certain circumstances); Wayne v. United States, 318 F.2d 205, 212 (D.C. Cir.), cert. denied, 375 U.S. 860 (1963) ("[A] warrant is not required to break down a door to enter a burning home to rescue occupants or extinguish a fire, to prevent a shooting or to bring emergency aid to an injured person"); People v. Lanthier, 5 Cal.3d 751, 755 (1971) (warrantless search of lockers justified to identify source of noxious odor permeating surrounding area); State v. Hetzko, 283 So.2d 49, 52 (Fla.Dist.Ct.App. 1973) (police officers "had every reason to believe that the defendant was in distress or that some foul play had occurred"; they "would have been derelict in their duty" if they had not made a warrantless entry into the house). See generally 3 W.R. LaFave, Search and Seizure § 6.6 (3d ed. 1996).

Similarly, in the vast and much litigated domain of regulatory searches and seizures, the measure of compliance with the Fourth Amendment is certainly not whether a warrant appropriate to a criminal investigation might have been obtained or warrantless action in enforcement of the criminal law would have been justified. Rather, the question relates to the reasonableness of the action measured by the nature of the regulation being enforced and whether or not in the particular circumstances a warrant may reasonably be required. See, e.g., Griffin v. Wisconsin, 483 U.S. 868, 871-873 (1987) (probation officers' prerogative to conduct warrantless searches of probationers' homes for evidence of probation infraction upheld); Commonwealth v. Tart, 408 Mass. 249, 255 (1990), quoting New York v. Burger, 482 U.S. 691, 702 (1987) ("[A] warrantless administrative search to determine the permit status of a fishing vessel which is landing raw fish in the Commonwealth is 'necessary to further [the] regulatory scheme of [c. 130]'"); McCabe v. Life-Line Ambulance Serv., Inc., 77 F.3d 540, 547 (1st Cir.), cert. denied sub nom. McCabe v. Lynn, 117 S. Ct. 275 (1996) (city policy permitting forcible warrantless entry of private residence to enforce order accurately to identify and

promptly detain recalcitrant and dangerous mentally ill persons upheld); United States v. Green, 474 F.2d 1385, 1389 (5th Cir.), cert. denied, 414 U.S. 829 (1973) ("Until someone expert in the cause of fires arrives, inspects the scene, and determines that the fire has been completely extinguished, the firemen cannot reasonably depart. The imposition of a warrant requirement in such circumstances would immobilize the entire apparatus of fire protection"); Horner v. State, 836 P.2d 679, 682 (Okla.Crim.App. 1992) (warrantless inspection of salvage yard based on statutory regulation of industry was reasonable because State had substantial interest in regulating industry to control automobile theft).

To be sure, this case, like the Leonard case, involves not premises but a motor vehicle. But motor vehicle cases are but a species of a genus the members of which number in the hundreds. Indeed, it is standard lore that, if anything, motor vehicles are the occasion for less not more stringent constitutional safeguards than private premises. See Cardwell v. Lewis, 417 U.S. 583, 590 (1974) ("One has a lesser expectation of privacy in a motor vehicle because its function is transportation and it seldom serves as one's residence or as the repository of personal effects"); Carroll v. United States, 267 U.S. 132 (1925). And no basis in principle or practicality exists for departing from the fundamental touchstone of reasonableness in cases where a motor vehicle is searched or detained for other than law enforcement reasons. As the Supreme Court stated in South Dakota v. Opperman, 428 U.S. 364, 367-368 (1976), "[i]n discharging their responsibilities for ensuring public safety, law enforcement officials are necessarily brought into frequent contact with automobiles. Most of this contact is distinctly noncriminal in nature." And, of course, the exercise of this police function in respect to motor vehicles is neither novel nor infrequent. As the cases collected in the Appendix illustrate, courts all over the country have long recognized community caretaking as a constitutionally legitimate basis for action that constitutes a search or seizure.

Perhaps the court avoids this most natural and familiar analysis of this case out of a concern that the rubric of community caretaking is too amorphous and might be taken as offering the police carte blanche for intruding on the rights of citizens. But this is an unwarranted concern. As its text indicates, "[t]he ultimate standard set forth in the Fourth Amendment is reasonableness." Cady v. Dombrowski, 413 U.S. 433, 439 (1973). See Maryland v. Wilson, 117 S. Ct. 882, 884-885 (1997). Reasonableness is also the touchstone of art. 14. But reasonableness here as elsewhere is a legal conclusion, based on an objective reasoning ultimately disciplined and policed by the courts. That the test is one of reasonableness should not be misunderstood as authorizing law enforcement officers to stop and detain whomever they wish for whatever reason they like. The test of reasonableness in respect to criminal investigations, as in the case of Terry stops, depends on a balance between the law enforcement function claimed to justify it and the intrusions (with its attendant dangers of abuse) on the liberty of the citizen, and this balance must in the last analysis be presented to and pass muster in court. So too here, where the justification is the performance of the multifarious purposes gathered under the rubric of "community caretaking functions," the particular intrusion must be reasonable when balanced against the justification offered for it. The cases gathered in the Appendix generally speak to the need to strike such an appropriate balance. What is clear is that here too a court must be the ultimate arbiter of reasonableness. Perhaps the best and clearest statement of what reasonableness means in this community caretaking context was articulated in State v. Anderson, 142 Wis.2d 162, 168-170 (Ct.App. 1987):

"The ultimate standard under the fourth amendment is the reasonableness of the search or seizure in light of the facts and circumstances of the case. . . . In a community caretaker case, this requires a balancing of the public need and interest furthered by the police conduct against the degree of and nature of the intrusion upon the privacy of the citizen. . . . This test requires an objective analysis of the circumstances confronting the police officer, including the nature and reliability of his information, with a view toward determining whether the police conduct was reasonable and justified. . . . This test also requires an objective assessment of the intrusion upon the privacy of the citizen. . . . [T]his is essentially the Terry test, but applied in a community caretaker setting. Overriding this entire process is the fundamental consideration that any warrantless intrusion must be as limited as is reasonably possible, consistent with the purpose justifying it in the first instance. . . .

"We conclude that when a community caretaker function is asserted as justification for the seizure of a person, the trial court must determine: (1) that a seizure within the meaning of the fourth amendment has occurred; (2) if so, whether the police conduct was bona fide community caretaker activity; and (3) if so, whether the public need and interest outweigh the intrusion upon the privacy of the individual.

"As to the last factor — weighing the public need and interest against the intrusion — relevant considerations include: (1) the degree of the public interest and the exigency of the situation; (2) the attendant circumstances surrounding the seizure, including time, location, the degree of overt authority and force displayed; (3) whether an automobile is involved; and (4) the availability, feasibility and effectiveness of alternatives to the type of intrusion actually accomplished." (Footnotes and citations omitted.)

Finally, the analysis offered here is not at odds with that recently announced by the Supreme Court in Whren v. United States, 116 S. Ct. 1769, 1774 (1996), in which the Court held that if a police officer has an objective basis for suspecting that one kind of criminality, in that case a marginal civil traffic infraction, has occurred, it is irrelevant that the actual subjective basis for the police action may have been suspicion that a far more serious form of criminality was afoot, but one for which a reasonable basis for action did not exist. This holding cannot mean, and the Court does not say, that only if a police officer has an objective basis to stop a motor vehicle for law enforcement purposes, may he take such action. This would overrule sub silentio several of the Court's own cases and a vast body of jurisprudence elsewhere. Nor does the Court say that, where there are two equally sufficient bases for police intervention, a court must first reach for the criminal rather than the caretaking justification — that it must justify the nightstick before it justifies the helping hand.

In Whren, the officer asserted that he made the stop in order to give the driver a warning concerning traffic violations, and the United States simply argued that the officer's asserted ground was a lawful one. Id. at 1772. The Whren Court affirmed the defendants' convictions on being satisfied that this was a lawful ground for the stop. Likewise, in the instant case, the ground that the police officer articulated in his testimony and the one that the Commonwealth based its argument on was a constitutionally valid one.

APPENDIX.

Many Federal and State courts have held that law enforcement officials may approach and detain citizens for community caretaking purposes in a variety of circumstances without running afoul of the Fourth Amendment and equivalent State constitutional provisions. See, e.g., Easyriders Freedom F.I.G.H.T. v. Hannigan, 92 F.3d 1486, 1497 (9th Cir. 1996) (police can stop any motorcyclist wearing a helmet that looks like noncomplying variety, even though cyclist commits no offense if he lacks actual knowledge that the helmet does not comply, because stop serves dual purpose of identifying individuals who intentionally violate the law, and informing riders who are unknowingly wearing noncomplying helmets that their helmets do not comply and possibly will not protect them sufficiently); United States v. King, 990 F.2d 1552, 1560-1561 (10th Cir. 1993) (officer justified in detaining defendant's motor vehicle in order to inform defendant of hazardous conditions and to advise him to stop honking; handgun in plain view may have been lawfully possessed and so did not and was not claimed to give reasonable ground of suspicion, but detention by show of force nevertheless justified out of concern for officer's own safety and that of bystanders); Crauthers v. State, 727 P.2d 9, 10-11 (Alaska Ct. App. 1986) (where defendant stopped thirty feet before a yield sign and rolled down window of his motor vehicle, officer reasonably concluded that defendant was asking for assistance and was justified in activating overhead flashing lights and approaching defendant; citing Cady and declining to follow Dunbar); State v. Puig, 112 Ariz. 519, 520 (1975) (officer justified in stopping defendant's motor vehicle and requesting to see his license and registration after observing defendant giving a hand signal before a turn and therefore suspecting that his turn signals were inoperative); State v. Harrison, 111 Ariz. 508, 509 (1975) (officer justified in stopping defendant's motor vehicle after observing left tire of defendant's vehicle "bouncing"; "the state has a valid interest in the safety of its highways for travelers"); State v. Mitchell, 498 N.W.2d 691 (Iowa 1993) (trooper had legitimate public safety responsibility, arising from a burned-out taillight, to stop defendant even though no violation of law had occurred; there was no indication that articulated safety concern was a pretext); State v. Pinkham, 565 A.2d 318 (Me. 1989) (officer's observation of defendant motorist's misuse of marked lanes furnished sufficient reason to justify stop for purely safety purposes to advise defendant of his misuse; citing Cady); State v. Fuller, 556 A.2d 224 (Me. 1989) (officer was justified in stopping defendant's motor vehicle to advise him "to fix the headlights before getting stranded in the dark" where defendant's vehicle approached officer with its headlights blinking on and off, and officer "reasonably suspected that [defendant] may have been in trouble"); State v. Green, 133 N.H. 249, 256 (1990) (articulable suspicion of crime not needed where police "regulat[ing] the movements of civilians at crime scenes"); State v. Oxley, 127 N.H. 407, 411 (1985) (officer's stop of a motor vehicle is justified where officer's reason for stop was to ensure that furniture hanging out from the back of the motor vehicle did not fall onto the highway); State v. Maynard, 114 N.H. 525, 526-527 (1974) (officer's stop of a motor vehicle is constitutional if he does so reasonably and in good faith believing that driver "may be ill and physically unfit to drive"); State v. Martinez, 260 N.J. Super. 75, 78 (App. Div. 1992) (officer's stop justified where defendant was driving at an extremely low speed because such low speed was possibly an indication that there is something wrong with the driver or the motor vehicle, a threat to approaching vehicles, or an indication that the neighborhood is being "cased"); State v. Goetaski, 209 N.J. Super. 362, 364-365 (App. Div.), cert. denied, 104 N.J. 458 (1986) (officer's stop justified where defendant was driving slowly on shoulder of rural highway flashing his left turn indicator); State v. Konewko, 529 N.W.2d 861, 863 (N.D. 1995) (officer's opening driver's door of defendant's parked motor vehicle was justified because officer observed defendant sliding toward floor and door, and therefore probably thought defendant needed help); Wibben v. State Highway Comm'r, 413 N.W.2d 329, 333 (N.D. 1987) (officer was justified in approaching defendant who was sitting in her motor vehicle at 2:35 A.M. in a deserted parking lot after dispatcher relayed call from unidentified person who reported that a person fitting defendant's description was sick or intoxicated; driver's privacy interest "minimal"); Provo City v. Warden, 844 P.2d 360, 361, 365 (Utah Ct. App. 1992), aff'd, 875 P.2d 557 (Utah 1994) (stop justified out of concern for defendant's "mental stability and welfare" where two unidentified men approached officer and told him that defendant was seeking to use cocaine so he could "drive [himself] into a wall"); State v. Marcello, 157 Vt. 657, 658 (1991) (a passing motorist's tip — "there is something wrong with that man" — was sufficient to justify trooper's making a "public interest" stop to determine whether defendant needed assistance); Commonwealth v. Waters, 20 Va. App. 285, 291 (1995) (citing Cady "community caretaking" exception, officer's stop of defendant was justified as reasonable exercise of community caretaker function where defendant's unsteady walking led to reasonable belief that aid or assistance was needed); State v. Chisholm, 39 Wn. App. 864, 866-868 (1985) (officer's stop solely for purpose of informing defendant driver that his hat was in jeopardy of blowing out of bed of pickup truck was "reasonable" as a legitimate community caretaking stop; Dunbar noted and disregarded on authority of Cady).

But see, e.g., United States v. Gregory, 79 F.3d 973, 978-979 (10th Cir. 1996) (officer's stop of defendant's truck after it crossed into right emergency lane of highway, based on purported suspicion that defendant was impaired by alcohol or lack of sleep, did not meet reasonableness test of Fourth Amendment); United States v. Dunbar, 470 F. Supp. 704, 708 (1979) (officer's good faith belief that defendant was lost was not sufficient basis for stop of vehicle); Ozhuwan v. State, 786 P.2d 918, 921-923 (Alaska Ct. App. 1990) (the fact that defendant had parked her motor vehicle legally but in an area frequently used by minors to consume alcohol did not justify officer's activating of lights and thus seizing defendant); McDougal v. State, 580 So.2d 324, 325 (Fla.Dist.Ct.App. 1991) (officer's stop of defendant's motor vehicle to give defendant information he had sought from officer two weeks before was unjustified); People v. Deppert, 83 Ill. App.3d 375, 381 (1980) (officer's belief that defendant motorist was in need of assistance was insufficient to justify stop); Doheny v. Commissioner of Pub. Safety, 368 N.W.2d 1 (Minn.Ct.App. 1985) (officer's belief that driver was lost did not justify stop); State v. Brown, 509 N.W.2d 69 (N.D. 1993) (though officer may be fully justified in stopping vehicle to provide assistance, stop in instant case is invalid as officer failed to provide any clear reason for thinking defendant needed assistance); State v. Langseth, 492 N.W.2d 298, 301-302 (N.D. 1992) (officer's activation of his warning light and approaching a van stopped along a rural gravel road was unreasonable seizure); State v. Sarhegyi, 492 N.W.2d 284, 286 (N.D. 1992) (mere fact that defendant had parked his motor vehicle next to tractors and combines in a farm implement dealership at 1:30 A.M., and attempted to leave the area when officer approached did not justify stop); Barrett v. Commonwealth, 250 Va. 243, 247-248 (1995) (without deciding the applicability of community caretaking functions doctrine, the fact that defendant was driving partially on shoulder of road, partially on adjoining yard, and not entering highway was not sufficient to show that defendant needed police assistance); State v. Markgraf, 59 Wn. App. 509, 512-513 (1990) (radio dispatch informing officer that an occupant in a motor vehicle fitting description of defendant's motor vehicle was in trouble justified officer's initial contact, but because defendant told officer that he was all right, further inquiry was unjustified); State v. DeArman, 54 Wn. App. 621, 625 (1989) (despite officer's belief that defendant or his motor vehicle was disabled because vehicle remained motionless at a stop sign for forty-five to sixty seconds, this belief was dispelled when vehicle moved, and therefore stop was unjustified).